The present invention relates to a stack package, and more particularly to a stack package in which all stacked semiconductor chips equally discharge heat to the outside.
Semiconductor packaging technology continues to develop in response to the evolution of electronic appliances towards miniaturization and multi-functionality. For example, the increase in miniaturization has accelerated development of a chip scale package of a size approaching that of a chip. In addition, the increase in multi-functionality has accelerated the development of a stack package in which several chips capable of performing various functions are arranged in one package.
Semiconductor packages developed to adapt to the increasing miniaturization and multi-functionality of electronic appliances, when mounted to said appliances, often generate a substantial amount of heat that must be quickly discharged to the outside. If the heat generated in the semiconductor chips is not quickly discharged, the semiconductor chips' operational speed decreases. Further, an increase in internal temperature due to the generated heat causes serious damage to the semiconductor chips. As a result, a heat sink is often created on the upper surface of the semiconductor chip or semiconductor package in order to aid in the dissipation of the generated heat. However, formation of such a heat sink on the upper surface of a semiconductor package increases the overall thickness of the semiconductor package, thereby degrading the value of the end product.
Also, when a heat sink is formed on the upper surface of a stack package, only the heat generated in the uppermost semiconductor chip is quickly discharged. Heat dissipation efficiency gradually decreases from the uppermost semiconductor chip to the lowermost semiconductor chip; therefore, the heat generated in the remaining semiconductor chips cannot be discharged as quickly as the heat generated in uppermost semiconductor. Since nearly all of the heat generated in the lowermost semiconductor chip of a stack package is not discharged, the lowermost semiconductor chip is likely damaged or the overall performance of the semiconductor package is likely degraded.